Container sizes for coco coir

For those who grow in coco, have you found any benefit to finishing your grow in a container larger than 1 gallon? I’ve always finished with a 3 gallon container, but is that really necessary for a soilless grow?

I’m considering experimenting with the two Humboldt Pistachio girls I’ve started, where I’ll only finish one in a 3 gallon container. I’ll be using air pots.

Thoughts? Opinions? Experiences? Guesses?

Both are 17 days old and using coco from the same batch. I’m not sure why the one is stunted. Oh well.

I’m only on my second grow in coco but I would think that it’s similar to pot size for soil. The more room for roots, the bigger the plant. I could be wrong tho

The same thought is why I’ve always finished big. I’ve read one plant expert say you’re really growing roots, so you may be right.

After re-reading this article I may abandon my experiment:

I would think small coco pots would be killer for an SOG run, which I plant to try eventually. I’m really digging the coco in my octopots tho, explosive growth compared to soil

I haven’t tried SOG yet, I’ve had great success using the manifold/mainline technique though.

Container size matters a lot less with coco but there is a limit on how small you can go and still get good results from what I have seen in my current run. At the start when I was transplanting I had a plant left over and it stayed in a 500ml pot for the entire grow. Even with constant access to water and nutrients it didn’t put on anywhere near the weight as the same strain in an 8L pot right next to it with the same diet and environment. I’ll get a pic in a little while when the lights go on to show the difference.

There is no one size fits all container, it depends on what size plants you’re growing and the feed program . . . it’s been my experience that when properly fed coco will support 2-4 times the plant mass as a comparable container in a soil grow.

I ran 3 gallon for years but found that to be excessive for the smaller plants (6-10 oz dry yield) I run now and have gone back to finishing in 2 gallon pots, GH nutrients in HFF/DTW.

I stay away from the grow bags and air pots that “air prune” the roots . . . when properly fed in the correct container size the root mass will develop a dense web of smaller roots, no long running roots that wrap around the container and no need to restrict root development through pruning. Adding something like GH Rapid Start will increase branching and the root mass’s ability to support a larger plant overall.

I think the real question is whether you’re using organic or mineral fertilizer. With organic fertilizer, the rule is “bigger roots, bigger fruits,” because you build up a microbiome over time that breaks down the nutrients and makes them available to the plant. With mineral fertilizer, the nutrients are already broken down and therefore directly available to the plant. That’s why you should apply mineral fertilizer in smaller targeted amounts but more frequently than with an organic fertilizer, and then you don’t necessarily need a huge pot to grow a huge plant.

Good info, thanks!

500ml is a bit extreme, though not much different from these Solo Cup challenges I’ve heard of. Looks like you still got a decent crop from it.

I also use high frequency fertigation. I’ve drawn a blank on what DTW stands for.

I don’t know if the Rapid Start I bought was just old or from a bad batch, but it was just a large clump of slimy material in a bit of liquid. I managed to break most of it up and dissolved but it was a pain, and I’m not convinced it helped enough to bother.

I agree. The only organic I use is raw Yucca, all other nutes are minerals from General Hydro, and I fertigate 2-4 times per day, depending the growth stage and on how often it needs it.

Beautiful grow in your pic!

DTW = Drain to Waste, no recirculation runoff goes down the drain

Ah, yes, all runoff is drained into cups below the pots, where I keep an eye on runoff ECM/PPM.

I should invest in better saucers. lol

Rapid Start should be liquid, no slim or lumps. Did the bottle have both caps, the plug and the screw top? Or was it one of the little 1 ounce plastic bottles?

It is super susceptible to airborne spores and has a short shelf life after opening compared to other nutrients. I buy gallons of all except the RS, I stick to 250 ml with it to avoid spoilage.

It’s the 1 oz/30ml bottle. It came sealed, I suspect it was old or maybe it was heated or frozen in transit. Maybe I’ll order another. I didn’t use it last year and it looked like I got good root growth and distribution without it.

It wasn’t bad considering the tiny pot. 8l or 2 gallon would probably be my lower limit after seeing the difference between them though.

that iz a true marvel to see ! I’ve noticed myceiling hasnt been mentioned at all , which is rather irrelevant in controlled indoor growing